The field of invention relates generally to imprint lithography. More particularly, the present invention is directed to a method of depositing and patterning materials on a substrate during imprint lithography processes.
Micro-fabrication involves the fabrication of very small structures, e.g., having features on the order of micro-meters or smaller. One area in which micro-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, micro-fabrication becomes increasingly important. Micro-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which micro-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary micro-fabrication includes forming a relief image in a structure by depositing a polymerizable fluid composition onto a transfer layer. The transfer layer may be a sacrificial layer providing a mask for patterning the substrate or the substrate itself. A mold makes mechanical contact with the polymerizable fluid. The mold includes a relief structure, and the polymerizable fluid composition fills the relief structure. The polymerizable fluid composition is then subjected to conditions to solidify and to polymerize the same, forming a solidified polymeric material on a transfer layer that contains a relief structure complimentary to that of the mold. The mold is then separated from the solid polymeric material such that a replica of the relief structure in the mold is formed in the solidified polymeric material. The solidified polymeric material is subjected to an environment to selectively etch the transfer layer relative to the solidified polymeric material such that a relief image is formed in the transfer layer. With this process, patterns with features on the scale of a few nanometers may be formed. As a result, substrates may demonstrate extreme topologies when compared to the dimensions of features formed thereon, wherein such extreme topologies may potentially prevent accurate reproduction of the pattern in the solidified polymeric layer.
In order to maximize the throughput and to minimize the cost of micro-fabrication, the size of the wafer being patterned is increased. However, increasing the wafer size may exacerbate the non-planarity of the substrate being patterned, and may also increase the filling time needed to dispense the polymerizable fluid composition upon the substrate.